// const 常量   不可更改
// const a: number = 10;

/**在类中定义常量 */
// readonly 只读
// class Http{
//     public static readonly baseUrl = "https://www.baidu.com"
//     public static str:string = "lisi"
// }

// Http.baseUrl = "https://www.douban.com"
// Http.str = "zhangsan"